Wafer-level testing includes testing dice on a wafer. In this specification, “dice” is used as the plural of “die”. A probe card may be used in testing dice on a wafer. Today's probe cards and packaged device test boards include a switching network to multiplex channels passing to and from devices being tested (e.g., radio transceivers for an RF probe card) down to a manageable number of channels that can be tested relatively quickly. These switching networks may be complex to design and may be finely-tuned to reduce their impact on the tests being performed. Such switching networks may be constructed of stripline layers within the probe card or packaged device test PCB (printed circuit board), as well as components on the surface of those boards connected with coplanar waveguides.
Test circuitry, such as the switching matrix, should have a good electrical path (e.g., low loss, low inductance, and low crosstalk) to test a die accurately.